Transcription of TSH, Ultrasensitive 8660X - Quest Diagnostics
1 180 Clinical Use Diagnose hypo- and hyperthyroidism Monitor T4-replacement or T4-suppressive therapy Quantify TSH levels in the sub-normal rangeReference RangeInterpretive Information Primary hypothyroidism Decreased thyroid reserve (sub-clinical hypothyroidism) TSH-dependent hyper-thyroidism Thyroid hormone resistance Graves disease Autonomous thyroid hormone secretion TSH deficiencyClinical BackgroundThe serum TSH measurement is 1 of the most important tools in the diagnosis of thyroid disorders. TSH secretion from the pituitary gland is controlled by hypothalamic TRH and a negative feedback effect from circulating, free thyroid hormones.
2 Thus, in subjects with a normal hypothalamic-pituitary system, thereis an inverse correlation between free thyroid hormone and TSH concentrations in serum. Increased serum TSH is an early and sensitive indicator of decreased thyroid reserve and overt primary hypothyroidism. A third-generation TSH assay using chemiluminescent technology produces functional sensitivities of mU/L, permitting reliable quantification of serum TSH concen-trations in the subnormal range. This allows differentiation of euthyroid from hyperthyroid patients. This assay also helps diagnose essentially all patients with TSH-independent hyperthyroidism (Graves disease, etc.)
3 With a single blood sample. In addition, the assay allows adjustment of exogenous thyroxine dosage in hypothyroid patients and in patients on suppressive thyroxine therapy for thyroid Immunochemiluminometric assay (ICMA) Analytical sensitivity: mU/LSpecimen Requirements2 mL refrigerated serum (no additive red top tube); mL minimumAdultsmU/LMen and non-pregnant women1st dNot established*1-4 *TSH levels decline rapidly during the first week of life in most children, but may remain transiently elevated in a few individuals despite normal free T4 levels. For confirmatory testing following a newborn thyroid screen, a free (or total) T4 level is usually required for proper interpretation of TSH levels in this age , Ultrasensitive8660X
